Ditches formed in the earth for conveying water to a point or to an area of use have been common throughout the world for generations. Earthen ditches have been used to transport potable water, irrigation water and other fluids and materials. Earthen irrigation ditches continue to be significant in the transportation of water because they are readily and inexpensively formed in almost any terrain.
The term “ditch” as used in this document means any excavation dug in the earth, or any structure partially or completely installed above earth, that may be referred to as a drain, channel, canal or acequia, whether lined or unlined, usually but not always relying primarily on gravity to transport fluids and materials along descending elevations.
During transportation of water through earthen ditches that are unlined by a material other than dirt (“unlined ditches”), significant quantities of that ever more precious commodity, water, are lost because of seepage, erosion, trans-evaporation and other causes. Tests indicate that as much as 80-90% of water may be lost during transportation through an unlined earthen ditch before water is delivered to a point or area for application and use.
It also should be appreciated that loss of water, referred to as “seepage loss,” may be considerable. At least one report issued by New Mexico State University entitled “Field/laboratory Studies for the Fast Ditch Lining System,” dated Feb. 10, 2002 (“Report”), indicates the results of tests conducted over a nine day interval. Total water losses during the nine-day test period were estimated to be 14,245,010 gallons, or 85.8% of total flow, when water was conducted through an unlined earthen ditch. The Report attributes most water losses to existing vegetation overgrowth, tree root systems, gopher holes, evaporation, and seepage or percolation. On the other hand, that same report, based on field measurements taken with a liner system disclosed in at least one of the Fast Ditch Patents and Applications (a term defined below) that had been installed in the same earthen ditch showed a total loss of only 7.3% of total flow.
Unlined earthen ditches must regularly be maintained, cleaned and repaired to avoid loss of water through wall collapse, accumulated debris, absorption through dirt walls, capillary action, rodent activity, among many causes of ditch deterioration. Because repair and maintenance of unlined ditches is costly and labor intensive, various methods for lining unlined ditches have been suggested. Those methods include use of concrete, metal, and polyvinyl chloride materials. Those suggestions, however, have proven inadequate for a number of reasons including at least cost and unresponsiveness to modern environmental concerns. Some materials, like concrete, are difficult to install in remote geographical areas, are inflexibly positioned once installed, and often require major construction efforts that are neither practical nor affordable based on cost-benefit analyses.
Exemplary solutions to problems associated with lining both lined and unlined ditches have been provided in the following patents and patent applications by one or more of the inventors named in connection with this document: U.S. Pat. No. 6,273,640 issued Aug. 14, 2001; U.S. Pat. No. 6,692,186 issued Feb. 17, 2004; U.S. Pat. No. 6,722,818 issued Apr. 20, 2004; U.S. Pat. No. 7,025,532 issued Apr. 11, 2006; U.S. Pat. No. 7,165,914 issued Jan. 23, 2007; U.S. Pat. No. 7,156,580 issued Feb. 2, 2007; U.S. Pat. No. 7,357,600 issued Apr. 15, 2008; U.S. Pat. No. 7,470,085 issued Dec. 30, 2008; and application Ser. No. 12/100,829 filed Apr. 10, 2008 (collectively, “FastDitch Patents and Applications”).
The FastDitch Patents and Applications, and this document, describe and claim apparatus that provide ditch liner sections that are inexpensive, light, portable, light-resistant, and ultra-violet resistant. The FastDitch Patents and Applications, and this document, also describe and claim liner sections that are easily inter-connectable and, when assembled, are capable of transporting desirable and undesirable fluids and materials through the liner sections quickly and efficiently. The liner sections may be installed using simple, conventional tools such as a shovel, cordless drill, rubber mallet and sledge hammer. When installed, the liner sections are substantially maintenance free. In an installation in which the flow of fluids and materials is approximately 2.00 feet per second, the assembled liner sections are self-scouring. The liner sections are corrugated, and at least one additional mechanical advantage thus provided is flexibility of interconnected liner sections to accommodate the contours of an existing ditch, whether lined or unlined. The corrugations also allow an installed water management system to flex during freeze-thaw fluctuations. The liner sections also are environmentally safe, nontoxic, and recyclable because made of selective plastics. At least one plastic used to manufacture the liner sections is Nora Chemicals NOVA POL® TR-0535-UG Hexene MDPE. The Fast Ditch Patents and Applications describe and claim liner sections that reduce loss of desirable fluids during such transportation.
As indicated, use of concrete to line ditches has proven particularly problematic. Since the advent of concrete and other building materials made by mixing a cementing material such as Portland cement with both a mineral aggregate such as sand and gravel, and sufficient water to cause the cementing material to set and bind the entire mass, concrete and similar materials have been used to line earthen ditches.
Originally it was thought that concrete lined ditches would avoid loss of water through seepage through the concrete into the underlying earth. Experience has demonstrated, however, that whether freestanding or moving, fluids seep into, against, and under concrete concrete-lined ditches. This adversely affects commercial and residential structures, and causes loss of desirable fluids such as irrigation water. Unfortunately, concrete also has inherent brittle tendencies to crack. It is difficult to repair in remote and challenging terrain due in part to the substantial weight of concrete, and the weight of hauling and installing equipment and vehicles. Concrete repairs also may disrupt landscapes due to the heavy equipment needed to haul and emplace concrete. Accordingly, corrosion mitigation in connection with concrete used for lining ditches has been a significant goal, but difficult to achieve.
At least one reason for difficulty in corrosion mitigation in concrete lined ditches is the fact that concrete drains manufactured from Portland cement and various aggregates are subject to deleterious damage caused at least in part by alkali-silica reactivity (“ASR”). ASR is a chemical reaction between Portland cement concrete and aggregates that in some environments, and under some conditions, may cause severe damage to concrete ditches. ASR also may expedite other reactions that in turn cause damage, such as freeze-thaw or corrosion related damage. The phenomenon has been recognized since at least 1940, but neither the mechanisms of ASR, nor solutions, yet are clearly understood.
It is known, however, that deterioration of a concrete structure such as a concrete-lined ditch is due at least in part to water absorption by a gel that forms in concrete. The term “gel” as used in connection with concrete fabrication refers to a naturally occurring silica gel that is a colloidal silica resembling course white sand, but has many fine pores, a condition that causes the gel to be extremely adsorbent. Soluble alkalis also are present in cement, and may be affected by undesirable moisture. Vulnerable sites in the silica structure may be attacked by fluid-induced activity, converting the silica to a silica gel that absorbs water or other fluids.
An important property of concrete is its tensile strength, or its ability to react to longitudinal stress. Liquids, however, are known to adversely affect tensile strength in concrete. If the tensile strength of concrete is exceeded, cracks will form and propagate from one or more alkali-silica reaction sites, weakening the concrete structure. Many if not all the problems generally associated with ASR may be seen in concrete-lined ditches that have been constructed in situ for any length of time. In addition, concrete is becoming ever more expensive due to international demand occasioned by countries that until recently lagged construction activities in the United States and Europe; indeed, at the time of this document, shortages in Portland cement and concrete have been reported.
Concrete also has several additional limitations and deficiencies as a liner material for earthen ditches. Material characteristics of concrete are not consistent, and usually are not even consistent within the same ditch line. Concrete ditch liners also react adversely to changes in ambient temperatures, and to rapidly altering hot and cold cycles. Concrete is subject to cracking due to temperature changes. If moisture penetrates cracks in concrete, a concrete lined ditch is subject to further cracking. Slight cracks tend to expand into large cracks as frost and thaw cycles proceed through a typical year. In the end, concrete lined ditches are subject to possible catastrophic failure. As a result, significant amounts of water may be lost when transported through concrete lined ditches. Significant quantities of water are lost because of seepage, erosion, trans-evaporation and other causes.
Concrete lined ditches also must regularly be maintained, cleaned and repaired to avoid further loss of water through wall collapse, accumulated debris, newly formed cracks and deterioration of the base and walls of concrete due to the continued effects of weather. Repair and maintenance of concrete lined ditches is costly and labor intensive. Patching concrete is expensive, labor intensive, and difficult to achieve given the remote location of most ditches, particularly agricultural ditches used to transport irrigation water. The repair problems associated with concrete lined ditches present major construction efforts that often are neither practical nor affordable. Therefore, many concrete ditches continue to deteriorate, resulting in increased loss of water. Inability to readily direct and redirect water flow to other ditches or in other directions using concrete or steel also is a significant limitation on their use.
In recent years, efforts have been made to develop methods to seal cracked concrete lined ditches. A variety of mortars and sprayed-on resins and plastics have been suggested. Unfortunately, both mortar and spray-on resins and plastics have proven inadequate solutions because of comparatively disadvantageous costs involved in the materials and applications processes, and because of labor costs associated with direct application of such materials at the site of a concrete lined ditch, regular often remote from where such materials are available. Further optimizations in connection with the FastDitch Patents and Applications have been introduced that provide alternative features and desirable elements for increasing the range and variety of differing applications and environments in which the water management system may be used.
For example, the mating, nesting, or connectable ends of liner sections in accordance with the FastDitch Patents and Applications allow compressible connection of liner sections end-to-end. This is achieved by providing for opposing male and female structural elements and components whose dimensions and shapes vary (collectively, “dimensionally different compressible components”). The FastDitch Patents and Applications also provide for liner sections whose corrugations vary in shape and configuration between opposing ends of a liner section. For example, U.S. Pat. No. 6,722,818 provides for a compressibly connectable member formed in the downstream end of a liner section. A coupling channel is formed in the upstream end of a liner section. Both the compressibly connectable member and the coupling channel are dimensioned to be substantially double the thickness of an intermediate body between the compressibly connectable member and the coupling channel in which corrugations are formed.
While the apparatus, methods and systems disclosed and claimed in the FastDitch Patents and Applications have proven useful in a variety of situations and installations, the flow control liner system described, illustrated and claimed in this document adds to the art by solving problems associated with the flow of fluids and materials through a liner section in the direction of a longitudinal axis perpendicular to a cross-section of a liner section. Also, the flow of fluids and materials against the exterior faces of the opposing walls of a ditch liner section that might otherwise cause erosion flow that might damage or displace one or more ditch liners in an assembled and installed flow control liner system, is solved by providing a plurality of subsurface aprons extending from the liner section.
The additional optimizations shown and claimed in this document provide a new and useful flow control liner system that results in an inexpensive, light weight, portable, light-resistant, ultra-violet resistant, inter-connectable system of liner sections that, when assembled, transport either desirable or undesirable fluids and materials through the flow control liner system, while reducing water loss, flow damages, and displacement of installed liner sections.